I don't know that the gender was changed to male the idea of a relationship between them more palatable so much as I suspect it was just that they had to put their own stamp on it somehow--beyond being a US version--and this is what they thought of

I am so curious if this is true. Because yeah, to me it smacked of 'let's genderswap to have a proper het romance' but you're totally right that it could've gone the other way - 'let's change things up and make Watson a lady! --Oh, and then we can have romance!' (I am convinced the romance is there somewhere, it's TV, it's how these things work. But I find the latter much less offensive.)

And yes, I don't get why they had to change Watson's backstory. It sounded like Holmes's is getting changed too - and I do wonder if they wanted to drop the war vet thing to avoid controversy? - but Watson in the original was always a competent doctor (...if not always an actively practicing one...) and why they'd take that away...doesn't bode well for their treatment of her character. :/